Environmental plastic degradation

Of the (estimated) 300 - 400 million tonnes of plastic produced worldwide every year, only around 20% is currently recycled or incinerated. Much of the remaining 80% eventually ends up in the environment.

In the environment, plastics are degraded by weathering, UV light, abrasion, and mechanical action etc - but they are also degraded by microbes (e.g. Proteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes) and by fungi.

Biodegradation of plastics has now been observed in polythene [PE], polypropylene [PP] , polystyrene [PS] , PVC and polyamides [PA] (e.g Nylon). The specific enzymes produced by the organisms, and which are responsible for the degradation, are for the most part unknown.

Although an increasing number of microorganisms have been isolated and identified recently, the responsible enzymes or associated degradation pathways are rarely identified for many types of synthetic polymers.

Source : Materials, 14, 3

Note : Although many research groups are currently investigating the possible uses of micro-organisms to potentially remove plastics and microplastics from the environment, the possible harmful effects of the degradation products are also largely unknown.

Also see : Microplastics and human health implicationsplugin-autotooltip__plain plugin-autotooltip_bigMicroplastics and human health implications

Note: Microplastic pollution is so widespread that it's now been found contaminating almost all multicellular lifeforms which have been tested. This article is only related to possible risks to human health. and Microplastic pollutionplugin-autotooltip__plain plugin-autotooltip_bigMicroplastic pollution

"Plastic waste is currently generated at a rate approaching 400 Mt [mega-tonnes] / year. The amount of plastics accumulating in the environment is growing rapidly, yet our understanding of its persistence is very limited."

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